Cylindrical Roller Bearings

4- Combinations of cylindrical roller bearings

Table 1 shows the representative combinations of bearings.

1. Bearings are manufactured in a set so that two bearings receive a load evenly; therefore, they must be assembled together with identically numbered bearings and not mixed with other arrangements.

2. Triplex arrangements of bearings are also available.

5- Tolerance of inscribed circle diameter and circumscribed circle diameter of rollers of interchangeable cylindrical roller bearings

Interchangeable cylindrical roller bearings are bearings having the same number in the group. The bearing function is not impaired even if an outer ring is combined with an inner ring with rollers or an inner #ring is combined with an outer ring with rollers.

6- Allowable speed of cylindrical roller bearing #ULTAGE series

As the rotational speed of the bearing increases, the temperature of the bearing also increases because of the friction heat produced inside the bearing. Operation at excessive temperatures will significantly deteriorate the lubricant performance, causing abnormal temperature rises and seizure. Factors affecting the allowable speed of bearings are as follows.

(1) Bearing type

(2) Bearing size

(3) #Lubrication (grease lubrication, circulating lubrication, oil lubrication, etc.)

(4) Bearing internal clearance (bearing internal clearance during operation)

(5) Bearing load

(6) #Shaft and housing accuracy

The allowable speed specified in the bearing catalogue is the reference speed limit which allows for satisfactory heat dissipation and lubrication conditions before adversely affecting the bearing.

Oil lubrication

The allowable speed for oil lubrication is the speed at which the outer ring temperature reaches 80°C with room temperature spindle oil (lubrication oil viscosity: VG32) supplied at 1 liter/min under an operating load of 5% of the basic static load rating C0r.

Grease lubrication

The allowable speed for grease lubrication is the speed at which the outer ring temperature reaches 80°C with lithium-based grease (consistency: NLGI3) filled 20%-30% of the free space under an operating load of 5% of the basic static load rating C0r.

In either of the lubrication methods, the bearing temperature rise differs if the usage condition (operating load, rotational speed pattern, lubricating condition, etc.) is different; therefore, the bearings must be selected with sufficient allowable speed.